Add a snippet to demonstrate icon disablement algorithms

This adds Snippet384 to inspect the behavior of different different
algorithms for the transformations of images to be used as disabled
versions.

Author: killingerm

examples/org.eclipse.swt.snippets/Snippets.md

@@ -214,6 +214,7 @@ To contribute a new snippet, [create a snippet contribution as a pull request](h
 - [draw an image scaled to half size and double size](https://github.com/eclipse-platform/eclipse.platform.swt/tree/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet355.java) – [(preview)](https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/examples/org.eclipse.swt.snippets/previews/Snippet355.png "Preview for Snippet 355")
 - [draw an image at various zoom/dpi levels](https://github.com/eclipse-platform/eclipse.platform.swt/tree/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet367.java) – [(preview)](https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/examples/org.eclipse.swt.snippets/previews/Snippet367.png "Preview for Snippet 367")
 - [draw a disabled/grayed image at various zoom levels](https://github.com/eclipse-platform/eclipse.platform.swt/tree/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet382.java) – [(preview)](https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/examples/org.eclipse.swt.snippets/previews/Snippet382.png "Preview for Snippet 382")
+- [compare algorithms for rendering disabled images](https://github.com/eclipse-platform/eclipse.platform.swt/tree/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet384.java) – [(preview)](https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/examples/org.eclipse.swt.snippets/previews/Snippet384.png "Preview for Snippet 384")
 
 ### **ImageData**
 - [display an animated GIF](https://github.com/eclipse-platform/eclipse.platform.swt/tree/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet141.java)